(a) Field of the Invention
The present invention relates to a method for channel quality estimation and link adaptation. More specifically, the present invention relates to an apparatus and method for channel quality estimation and link adaptation in orthogonal frequency division multiplexing (OFDM) wireless communication systems.
(b) Description of the Related Art
For an operation of wireless communication networks with an optimal throughput in a time-varying channel environment, appropriate link adaptation for communication links through which data transmission occurs is necessary.
Link adaptation is an approach for properly selecting parameters including transmit power or modulation mode according to the status of channels in a wireless communication environment, and maintaining an optimal throughput. The status of channels can be analyzed by different methods based on the measurements of bit error rate (BER) or packet error rate (PER), the number of packet retransmissions, or signal-to-noise ratio (SNR).
The related documents suggest a method of estimating the quality of communication links and determining an optimal data rate or an optimal length of packet using the estimated quality of communication links.
For example, D Qiao et al. published a related paper under the title of “Goodput Enhancement of IEEE 802.11 a Wireless LAN via Link Adaptation” (IEEE International Conference on Communications, 2001, Page(s) 1995 to 2000), which discloses a link adaptation method using the determination of a transmission mode as an existing link adaptation method in combination with the determination of the frame length to acquire an optimal throughput.
Another document concerned is “Adaptive Frame Length Control for Improving Wireless Link Throughput, Range, and Energy Efficiency (Proceedings, INFOCOM'98)” by P. Lettieri et al., which discloses a method of determining an optimal frame length so as to acquire an optimal throughput in a wireless communication system, thereby enhancing data rate and transmission distance.